Give your rifle a little more accuracy with the Browning BOSS-CR A-Bolt Muzzle Break. There are many advantages of Boss without a muzzle brake feature. It has a 1 piece, no hole accessory that is designed to fit only Bar MK IIs and A-bolt IIs previously factory fitted with Boss. The CR stands for conventional recoil and gives the shooter the option of shooting the BOSS system with standard recoil and muzzle blast.